1. Technical Field
The present invention relates in general to data communication networks and in particular to namesharing between multiple network adapters in a bridged network environment. Still more particularly, the present invention relates to a method and system for broadcast management in a bridged network environment that permits namesharing by multiple network adapters.
2. Description of the Related Art
In a computer network such as a conventional local area network (LAN) or a wide area network (WAN), communication between computers can be conceptualized using the International Organization for Standardization Open Systems Interconnection (ISO/OSI) model, which provides a multi-layered architecture that standardizes levels of service and defines types of interactions for computers engaged in communication across the computer network. Above the lowest, physical layer (Layer 1) of the ISO/OSI model is the data-link layer (Layer 2), which is principally concerned with the coding, addressing, and transmission of data between computers. Within the many common network topologies (e.g., token ring, token bus) falling within the set of IEEE 802 standards, the data-link layer of the ISO/OSI model conveys a network address known as a media access control (MAC) address that is unique for each device within a bridged network.
Because MAC addresses are simply binary numbers, they are inconvenient for network users and designers to use. Accordingly, it is frequently the case that logical alphanumeric names are supported by higher layers of the ISO/OSI model. For example, in networks that implement the network layer (Layer 3) of the ISO/OSI model with NetBIOS (Network Basic Input/Output System), 16-byte alphanumeric names are supported. Originally, as discussed in U.S. Pat. No. 4,930,159 to Kravitz et al., NetBIOS names were required to be unique within each bridged network to ensure proper authentication of attached devices. Later networks, however, such as that disclosed by U.S. Pat. No. 5,454,078 to Heimsoth et al., permitted NetBIOS names to be shared between network adapters, which advantageously resulted in greater distribution of network workload among network adapters.
The present invention includes a recognition that it would be desirable to implement broadcast management techniques in networks that permit namesharing between network adapters within the same bridged network. For example, some currently available networking products implement xe2x80x9cname caching,xe2x80x9d whereby a name caching entity caches the NetBIOS name and MAC address of each network adapter detected in a traditional LAN (e.g., Ethernet or Token Ring) or asynchronous transfer mode (ATM) emulated LAN. When a broadcast frame for a cached NetBIOS name is received by a name caching entity, the name caching entity converts the broadcast frame into a unicast frame using the MAC address associated with the NetBIOS name contained in the broadcast frame. In this manner, the number of broadcast frames in the network is advantageously reduced. While the present invention recognizes that it would be desirable to seamlessly implement both namesharing and broadcast management techniques such as name caching, the concurrent use of both enhancements in a bridged network environment is not currently feasible since name caching permits only a single MAC address to be cached with each NetBIOS name. The present invention is therefore directed to the interoperability of broadcast management techniques (in particular, name caching) and namesharing in a bridged network environment.
In accordance with the present invention, a data communication network includes a network client, a network server, and a name caching entity located between the network client and the network server. The network server is coupled to the data communication network by a plurality of network adapters that each have a different network (e.g., MAC) address, but share a common logical name. The name caching entity includes a name cache, which stores the common logical name shared by the server""s network adapters in association with the network address of one of the network adapters. By referring to the name cache, the name caching entity is able to convert broadcast frames to unicast frames, thereby advantageously reducing broadcast frames in the network. Failure to detect a frame indicating the establishment of a session with the network server within a selected interval of transmission of a frame requesting establishment of a session with the network server will cause the name caching entity to disassociate the logical name and the network address in the name cache. In this manner, the network client can establish a session with the network server through another network adapter in cases in which the network adapter whose network address is stored in the name cache cannot support an additional session.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.